SECTION 3.] 



SEEDLINGS. 



25 



plumule in time emerges is seen at the base, or near it ; so the caulicle is 



62 63 64 65 



extremely short, and does not elongate, 

 but sends out from its base a simple 

 root, and afterwards others in a cluster. 

 Not only does the cotyledon lengthen 

 enormously in the seedling, but (un- 

 like that of Iris, Indian Corn, and all 



Fig. 62. Germinating Onion, more advanced ; the chink at base of cotyledon 

 opening for the protrusion of the plumule, consisting of a thread-shaped leaf. 

 63. Section of base of Fig. 62, showing plumule enclosed. 64. Section of same 

 later ; plumule emerging. 65. Later stage of 62; upper part cut off. 66. A grain 

 of Indian Corn, flatwise, cut away a little, so as to show the embryo, lying on the 

 albumen, which makes the principal bulk of the seed. 67. A grain cut through the 

 middle in the opposite direction, dividing the embryo through its thick cotyle- 

 don and its plumule, the latter consisting of two leaves, one enclosing the other. 

 68. The embryo, taken out whole : the thick mass is the cotyledon ; the narrow 

 body partly enclosed by it is the plumule ; the little projection at its base is the 

 very short radicle enclosed in the sheathing base of the first leaf of the plumule. 



Fig. 69. Grain of Indian Corn in germination ; the ascending sprout is the first 

 leaf of the plumule, enclosing the younger leaves within ; at its base the primary 

 root has broken through. 70. The same, advanced; the second and third leaves 

 developing, while the sheathing first leaf does not further develop. 



